#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
#include <assert.h>
#include <string.h>
#include <algorithm>
#include <vector>
#include <string>
#include <map>
using namespace std;

namespace mystring
{
    class string
    {
    public:
        typedef char* iterator;
        typedef const char* const_iterator;

        iterator begin()
        {
            return _str;
        }

        iterator end()
        {
            return _str + _size;
        }

        const_iterator begin() const
        {
            return _str;
        }

        const_iterator end() const
        {
            return _str + _size;
        }

        string(const char* str = "")
            : _size(strlen(str))
            , _capacity(_size)
        {
            cout << "string(char* str) - 构造" << endl;
            _str = new char[_capacity + 1];
            strcpy(_str, str);
        }

        void swap(string& s)
        {
            ::swap(_str, s._str);
            ::swap(_size, s._size);
            ::swap(_capacity, s._capacity);
        }

        string(const string& s)
            : _str(nullptr)
        {
            cout << "string(const string& s) -- 拷贝构造" << endl;
            reserve(s._capacity);
            for (auto ch : s)
            {
                push_back(ch);
            }
        }

        // 移动构造
        string(string&& s)
        {
            cout << "string(string&& s) -- 移动构造" << endl;
            swap(s);
        }

        string& operator=(const string& s)
        {
            cout << "string& operator=(const string& s) -- 拷贝赋值" << endl;
            if (this != &s)
            {
                _str[0] = '\0';
                _size = 0;
                reserve(s._capacity);
                for (auto ch : s)
                {
                    push_back(ch);
                }
            }
            return *this;
        }

        // 移动赋值
        string& operator=(string&& s)
        {
            cout << "string& operator=(string&& s) -- 移动赋值" << endl;
            swap(s);
            return *this;
        }

        ~string()
        {
            cout << "~string() -- 析构" << endl;
            delete[] _str;
            _str = nullptr;
        }

        char& operator[](size_t pos)
        {
            assert(pos < _size);
            return _str[pos];
        }

        void reserve(size_t n)
        {
            if (n > _capacity)
            {
                char* tmp = new char[n + 1];
                if (_str)
                {
                    strcpy(tmp, _str);
                    delete[] _str;
                }
                _str = tmp;
                _capacity = n;
            }
        }

        void push_back(char ch)
        {
            if (_size >= _capacity)
            {
                size_t newcapacity = _capacity == 0 ? 4 : _capacity * 2;
                reserve(newcapacity);
            }
            _str[_size] = ch;
            ++_size;
            _str[_size] = '\0';
        }

        string& operator+=(char ch)
        {
            push_back(ch);
            return *this;
        }

        const char* c_str() const
        {
            return _str;
        }

        size_t size() const
        {
            return _size;
        }
        
    private:
        char* _str = nullptr;
        size_t _size = 0;
        size_t _capacity = 0;
    };
    string addStrings(string num1, string num2)
    {
        string str;
        int end1 = num1.size() - 1, end2 = num2.size() - 1;
        int next = 0;
        while (end1 >= 0 || end2 >= 0)
        {
            int val1 = end1 >= 0 ? num1[end1--] - '0' : 0;
            int val2 = end2 >= 0 ? num2[end2--] - '0' : 0;
            int ret = val1 + val2 + next;
            next = ret / 10;
            ret = ret % 10;
            str += ('0' + ret);
        }

        if (next == 1)
            str += '1';

        reverse(str.begin(), str.end());

        cout << "*****************************" << endl;

        return str;
    }
}


// 场景1
int main()
{
    mystring::string ret = mystring::addStrings("11111", "2222");
    cout << ret.c_str() << endl;
    return 0;
}
